Microsoft has a lot of database pilots and projects in the works, among them Katmai, Astoria, Jasper and Volta. But how do they all fit together?

Francois Ajenstat, director of SQL Server, explained to me this week how Microsoft's growing number of data-programmability pieces will come together over the next year or two.

All of what Microsoft lumps under "data programmability" falls under the domain of Ted Kummert, the Microsoft Corporate Vice President in charge of the data and storage platform division, Ajenstat said.

At the core of these different data-programmability projects is the concept of a common entity data model. EDM -- a way of describing entities and their relationships -- isn't new; it has been used by database programmers for more than 30 years. Ajenstat described EDM as a way of allowing programmers to program at a logical level, instead of a physical level.

Microsoft's goal is to enable LINQ, its Language Integrated Query extensions to the .Net Framework, to query the new ADO.Net Entity Model. Microsoft wants to simplify SQL Server developers' lives by freeing them up from having to understand SQL the language, said Ajenstat. On the path are a number of new products and services, among them:

* Astoria, which Microsoft released to testers in early May, allows programmers to work with data in the cloud. "We haven't talked about how, when or where we will release Astoria," Ajenstat said. "It might be a feature of a release of SQL Server. It might be a standalone product." The entity framework is a foundational piece of Astoria.

(A new, more user-friendly description of Astoria, courtesy of Microsoft blogger David Boschmans: "The technology code named Astoria is a technology that enables applications to expose data as a data service that can be consumed by web clients within corporate networks and across the internet. The use of web-friendly technologies make Astoria ideal as a data back-end for AJAX-style applications, Rich Interactive Applications and other applications that need to operate against data that lives across the web.")

* Jasper, which Microsoft released to testers in early May, is technology for building models on top of new data sources. As is true with Astoria, the ADO.Net Entity Framework also is at the core of Jasper. No word on when and how Microsoft plans to deliver the final version of Jasper.

* Volta is an academic incubation project focused on programming in the cloud, Ajenstat said. Volta has no connection to Astoria, Jasper or Katmai. Instead, it is focused on how you expose the Web Services and SOA data that is in the cloud, he said. Volta isn't about programming against hosted SQL Server; it's more futuristic than that.